Method and apparatus for simultaneous detection and measurement of charged particles at one or more levels of particle flux for analysis of same

Abstract

A charged particle detector and method are disclosed providing for simultaneous detection and measurement of charged particles at one or more levels of particle flux in a measurement cycle. The detector provides multiple and independently selectable levels of integration and / or gain in a fully addressable readout manner.

Description

[0001]This invention was made with Government support under Contract DE-AC05-76RLO1830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.FIELD OF THE INVENTION[0002]The present invention relates generally to a method and apparatus for simultaneous detection and measurement of charged particles at one or more levels of particle flux in a measurement cycle for analysis of same.BACKGROUND OF THE INVENTION[0003]Charged particle detection is necessary for the identification, monitoring, and concentration determination of chemicals, particulates, and aerosols in the gas phase. The detection of charged particles, or ions, can be accomplished using single, multiple, or array detector devices. Such ion detectors are useful in analytical instrumentation such as mass spectrometers, ion mobility spectrometers, and aerosol / particle counters, among others. Commonly desired features of ion detectors in such applications are high sensitivity, uniformity of...

AI Technical Summary

Benefits of technology

[0005]In situations where complex mixtures of charged particles exist, simultaneous observation of all ionized species is highly desirable; detection efficiency can thus be high (100%), inter-signal variation (noise) can be minimized, and artifacts associated with scanning (timing skew) can be eliminated. Described herein is a charged particle detector incorporating such characteristics, referred to as a “simultaneous” detector. In addition, levels or intensities of charged particles in complex mixtures can vary widely, complicating authentic and accurate reading of particle number (the number of charged particles) or the level of charged particles (e.g., low, medium, or high). Detection of very low particle numbers requires a highly sensitive and discriminating response. A very high level of charged particles may overwhelm or saturate detector response. A method of charged particle detection that accurately records abundance of all species, at their various low, intermediate, and high flux levels is desirable. A detection method described herein with such characteristics can be expected to provide a high linear dynamic range. Further, a detector that can be selectively set to appropriately observe and record any / all signals at an ideal scale (i.e. at a readout level that is not too low or too high for each / every observed signal) can be expected to provide a genuine and accurate recording of all charged particle signals. This capability can be achieved by automatic and judicious selection and / or setting of the amplification or gain associated with the electronics of the detector. Versatility in achieving such capability can be enabled by incorporating multiple levels of gain or amplification in the detector circuitry. A detection method incorporating such capabilities (as described herein) is referred to as “automatic” or “selective” gain, and implicitly necessitates multiple gain levels from which to choose. A charged particle detector capable of simultaneous, selective, and high dynamic range readout characteristics would be further valued if various charged particle signals could be accessed, read, and stored in a fully independent manner, rather than in a regular, fixed, or predetermined sequence (e.g. low-to-high mass or high-to-low mass or left-to right channel or right-to-left channel). With such capabilities, any detector channel(s), whether single or multiple, contiguous or not, can be accessed and read out at will for the desired purpose. Such a detector capability (described further herein) is referred to as a “random access” or an “independent access” or “fully addressable” readout capability. In one embodiment, a charged particle detector having all of the above desired detection characteristics is provided in a discrete electronics package or circuitry providing for facile detection of any type and any level of charged particles. In another embodiment, a charged particle detector having all of the above desired detection characteristics is of a hybrid design. In yet another embodiment, a charged particle detector having all of the above desired detection characteristics is fully integrated in a single (monolithic) electronic device or “chip” that includes all necessary detector circuitry.

Problems solved by technology

A very high level of charged particles may overwhelm or saturate detector response.

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